The invention relates to a process and apparatus for treating polishing cloths by the action of a liquid. More particularly, it relates to such a process and apparatus used to treat cloths utilized in the polishing, in particular, of semiconductor wafers.
In the chemomechanical polishing of wafers, in particular semiconductor wafers, one or both wafer surfaces are treated with the aid of polishing cloths to which a polishing agent generally based on silicates or silicic acids is applied. The polishing cloths are stretched over a moving, usually rotating, flat polishing surface and both the abrasion and also the geometrical quality of the polished wafers obtained are found by experience to decrease with increasing duration of use of the polishing cloths. In order to counteract this effect which occurs equally for both single-sided and double-sided polishing, it is proposed in the article by E. Mendel, P. Kaplan and A. V. Patsis entitled "Pad Materials for Chemical-Mechanical Polishing" printed in IBM Technical Report TR 22.2341, dated Apr. 10, 1980 (and substantially made available to the public at the Spring Meeting of the Electrochemical Society in Boston, Mass. on May 10, 1979) to regenerate polishing cloths which are diminishing in performance by rinsing them with a 10% methanol/water mixture and additionally brushing them off with fiber brushes. Although such a treatment is capable of counteracting the decrease in abrasion rates they are not capable of stopping the gradual deterioration in the wafer geometry, for instance in relation to the flatness, which is observed with increasing polishing cloth service life. Variations in both parameters are equally disadvantageous for a polishing process on a production scale.